1. Field of the Invention
The present invention relates to an assembling method of a tire and a wheel rim, which can lighten a gravity of a balance weight for correcting a weight unbalance in an assembled structure of the tire and the wheel rim.
2. Description of the Related Art
When a weight unbalance exists in an assembled structure of a tire and a wheel rim, the weight unbalance causes a vehicle vibration. Therefore, in order to reduce the weight unbalance mentioned above, it has been conventionally, generally carried out to assemble the tire in the wheel rim in a state of aligning a phase of an air valve position regarded as a heavy point of the wheel rim with a phase of a light point of the tire. Thus, it is possible to cancel a part of the weight unbalance, so that it is possible to reduce the gravity of the balance weight for correcting the weight unbalance in the assembled structure of the tire and the wheel rim.
However, the balance weight mentioned above is normally mounted to the leading end of the rim, thereby deteriorating an outer appearance and causing a cost increase. Therefore, it is desired to further reduce the weight.
In view of such a circumstance, the present inventor has conducted studies. As a result, the present inventor has found that the effect of canceling the weight unbalance can be enhanced and the gravity of the balance weight can be more reduced, by assembling the tire and the wheel rim while taking into consideration a Radial Runout (RRO) corresponding to an eccentricity of the wheel rim.
More specifically, the wheel rim 1 generally has an average RRO of the order of 0.4 mm and, as conceptually shown in FIG. 5A, a center displacement δ is generated between a center of rotation i and a center j of an outer periphery of a rim sheet 1a. On the other hand, the tire 10 is approximately concentrically attached to the rim sheet 1a. Therefore, a moment corresponding to a product Tt×δ of a tire weight Tt and the displacement δ is applied around the rotation center i, and a further weight unbalance is generated.
Accordingly, it has been found that the effect of canceling the weight unbalance can be more enhanced, and the gravity of the balance weight can be further reduced, on the basis of the following matters (1) and (2), as conceptually shown in FIG. 5B.
(1) A vector {right arrow over (Wc)} of a correction unbalance is determined by adding a vector {right arrow over (Wub)} of a weight unbalance of a wheel rim itself to a vector {right arrow over (W1)} of a weight unbalance based on the RRO.
(2) The tire and the wheel are assembled by aligning a phase of the vector {right arrow over (Wc)} with the phase of the light point of the tire.